VoIP terminal having QoS monitoring function and QoS monitoring method

ABSTRACT

A Voice over Internet Protocol (VoIP) terminal has a Quality of Service (QoS) monitoring function and uses a QoS monitoring method. In a VoIP system performing real-time voice communication over an IP network, a packet loss value and a time-axis index value are detected, and are calculated from a real-time transport protocol (RTP) packet and an RTP control protocol (RTCP) packet, a QoS state value of the network is obtained in real time, the detected QoS state value is compared to a preset QoS state table, and thus a QoS state of the IP network is displayed for users.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, andclaims all benefits accruing under 35 U.S.C. §119 from an applicationfor VoIP TERMINAL PROVIDED FUNCTION OF QoS MONITORING METHOD, earlierfiled in the Korean Intellectual Property Office on 19 Aug. 2005 andthere duly assigned Serial No. 10-2005-0076312.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a Voice over Internet Protocl (VoIP)terminal having a Quality of Service (QoS) monitoring function and a QoSmonitoring method.

2. Description of the Related Art

Generally, VoIP is a protocol for transferring video, voice and FAXmessages over the Internet. With VoIP, a user accesses the Internetusing a personal computer (PC) or an independent IP-based device totransmit/receive voice, as the user makes a call to a gateway using aconventional public switched telephone network (PSTN) terminal, or totransmit/receive real time media such as video.

A VoIP end-point device (e.g., a gateway, an IP phone, or a PC) of asender continuously exchanges real-time transport protocol (RTP) voicepackets with a recipient to conduct voice communication through RTP onan IP network. The VolP end-point device transmits and receives QoSinformation, such as packet loss value, jitter and delay, and RTPcontrol protocol (RTCP) information including call session information,to and from the recipient at uniform intervals.

RTP is a protocol for transferring real-time data, such as audio orvideo data, over a multicast or unicast network. The RTP does notprovide a connection, generally operates as an upper layer of a userdatagram protocol (UDP), and uses multiplexing and checksum features ofthe UDP.

The RTCP periodically transmits a control packet to a recipient usingthe following messages: a sender report (SR) includingtransmission/reception statistics information of an active sender; and areceiver report (RR) including transmission/reception information ofparticipants, not an active sender, a source description (SDES)describing a CNAME and a source name, BYE indicating termination of anRTP session, and application (APP) specifying a function confined to theapplication upon testing a new application or a new function. The RTCPpacket has a fixed header field and a variable field having a lengthvarying with the type of packet. For effective information, several RTCPpackets may form one UDP packet.

Recently, a Voice over Wireless LAN (VoWLAN; wireless Internettelephone) technology transmitting voice over a WLAN, which is the mostwidespread wireless technique, has emerged as a new mobile telephonetechnology, just as VoIP systems have emerged as a new wired telephonetechnology. This is because the VoWLAN is inexpensive and convenientbecause of its mobility, in addition to its having the benefits of wiredInternet telephone VoIP.

The VoWLAN transmits voice data over the WLAN. Typical Internettelephones operate on a wired network, while the VoWLAN uses the WLAN asa medium.

The VoWLAN can provide convenient voice communication because of itsguaranteed mobility within a coverage area of an access point (AP). Inaddition, the VoWLAN can provide significant cost savings compared toline-based telephoning since it uses a pre-built network. Particularly,the VoWLAN is advantageous for its ability to adapt to the needs of thefuture, for example, video telephoning.

Since all voice data in the VoIP are composed as RTP packets and arecontinuously transmitted over a data network, the VoIP needs a certainnetwork bandwidth to enable smooth communication.

Since VoIP technology uses communication channels of a datacommunication network (Internet), voice data may be affected by delay,jitter, or loss on the network, as normal data is.

For this reason, measurement of QoS in a VoIP service requires diagnosisof a state of the network. In a QoS measuring method in a voicecommunication system using conventional VoIP technology, a trafficmeasuring device is connected to a VoIP packet path to directly parsethe VoIP packet, or a QoS state monitoring system is developed tocollect data.

However, the QoS measuring method in the voice communication systemusing conventional VoIP technology requires a separate device or system.

Furthermore, since provided values themselves are sub-classified intodelay (RTT), jitter, and loss, quality of actual VoIP service may dependon a manager's knowledge and experience. In this regard, the delay (RTT)refers to time measured from the moment a receiving terminal receivespacket data from a transmitting terminal until the moment the receivingterminal transmits packet data back to the transmitting terminal.

Also, even in the same network state, terminals having different typesor characteristics may be influenced differently. As this has not beenconsidered, the conventional art is not capable of providing optimalfunctions according to the type or properties of a terminal.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a VoIP terminalhaving a QoS monitoring function and a QoS monitoring method, andcapable of monitoring a QoS state of a network without using anadditional QoS monitoring device.

According to an aspect of the present invention, a VoIP terminal detectsa QoS state value from RTP and RTCP packets received from a terminal incommunication over a network, and compares the detected QoS state valueto a preset QoS state table so as to display a QoS state for users.

The VoIP terminal comprises: a first detector for detecting a packetloss value and a jitter value from the RTCP packet received from theVoIP terminal in communication; a second detector for calculating an RTTvalue from the RTP and RTCP packets received from the terminal incommunication, and for adding the jitter value detected by the firstdetector to the RTT value to obtain a time-axis index value; and acontroller for detecting the QoS state value from the packet loss valueand the time-axis index value which are obtained by the first detectorand the second detector, respectively, and for comparing the detectedQoS state value to the QoS state table to display the QoS state.

The controller may use Equation 1 to calculate the time-axis indexvalue:T_(m)=D_(r)+(W_(j)SJ),  Equation 1where T_(m) indicates a delay time value measured by the terminal, D_(r)indicates an RTT value calculated by the terminal, W_(j) indicates aweight of a jitter value, and J indicates a detected jitter value.

The QoS state table may include at least one of a network delay timevalue, the packet loss value, and the QoS state value. The QoS statetable uses Equation 2 to calculate a network delay time value in a busystate:Ti=(D_(g)S2)−D₁,  Equation 2where D_(g) is a one-directional delay value of G.114, and D1 is an RTPpacket processing delay value of a terminal.

The RTP packet processing delay value (D₁) of the terminal may includeat least one of a minimum processing time dependent on the type of aCODEC used in a busy state, a frame size of voice data, a capacity of ajitter buffer, a type of an echo canceller, a delay time in a routinefor enhancing quality of voice, and an additional network functionprocessing time (NAT, IPsec, etc.) used in the terminal.

The QoS state value of the QoS state table maybe obtained from anintersection between the network delay time value on an x-axis and thepacket loss value on a y-axis. A QoS state value of the QoS state tablemay include at least one of “Good,” “Fair,” “Poor,” and “Bad”, whichindicate QoS classes.

The VoIP terminal may include a logging function for performingselective storage only when a quality issue is caused in network stateinformation. The VoIP terminal may limit maximum storage capacity ofstored network state data using a circular queue.

According to another aspect of the present invention, a QoS monitoringmethod in a VoIP terminal comprises the steps of: detecting a packetloss value and a jitter value for an RTP session from an RTCP packetreceived from a terminal in communication; calculating an RTT value;adding the detected jitter value to the RTT value to obtain a time-axisindex value; obtaining a QoS state value from the detected packet lossvalue and the time-axis index value; and comparing the obtained QoSstate value to a QoS state table to display a QoS state.

According to yet another aspect of the present invention, a QoSmonitoring device comprises: a QoS state table including a network delaytime value, a packet loss value, and a QoS state value; a first detectorfor detecting a packet loss value and a jitter value from an RTCP packetreceived from a terminal in communication; a second detector forcalculating an RTT value from an RTP packet and the RTCP packet whichare received from the terminal in communication, and for adding thejitter value detected by the first detector to the RTT value to obtain atime-axis index value; and a controller for obtaining a QoS state valuefrom the packet loss value and the time-axis index value, which areobtained by the first detector and the second detector, respectively,and for comparing the obtained QoS state value to the QoS state table todisplay a QoS state of the network.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings, in which likereference symbols indicate the same or similar components, wherein:

FIG. 1 is a functional block diagram illustrating a VoIP terminal havinga QoS monitoring function according to an exemplary embodiment of thepresent invention;

FIG. 2 is a graph illustrating a QoS state table in the VoIP terminal ofFIG. 1;

FIG. 3 illustrates a QoS state of a network in the VoIP terminal of FIG.1;

FIG. 4 illustrates a circular queue used to limit data storage capacityin the VoIP terminal of FIG. 1; and

FIG. 5 is a flowchart illustrating a QoS monitoring method in a VoIPterminal according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a VoIP terminal having a QoS monitoring function and a QoSmonitoring method according to exemplary embodiments of the presentinvention will be described in detail with reference to the accompanyingdrawings. It is to be understood by those skilled in the art that thesystem configuration described below is illustrative only, and thepresent invention is not limited to such a configuration.

FIG. 1 illustrates the configuration of a VoIP terminal according to anexemplary embodiment of the present invention. The VoIP terminal 1includes a first detector 100, a second detector 200, a controller 300,and a QoS state table 400.

The first detector 100 detects a packet loss value and a jitter valuefrom an RTCP packet received from a terminal in communication over an IPnetwork 3.

The second detector 200 calculates an RTT value from an RTP packet andthe RTCP packet which are received from the terminal in communicationover the IP network 3, and adds the jitter value detected by the firstdetector 100 to the RTT value in order to obtain a time-axis indexvalue.

The controller 300 obtains a QoS state value from the packet loss valueand the time-axis index value, which are obtained by the first detector100 and the second detector 200, respectively, and compares the obtainedQoS state value to the QoS state table 400 so as to display a QoS stateof the network. The controller 300 uses Equation 1 to calculate thetime-axis index value:T_(m)=D_(r)+(W_(j)SJ),  Equation 1where T_(m) indicates a delay time value measured by the terminal, D_(r)indicates an RTT value calculated by the terminal, W_(j) indicates aweight of a jitter value, and J indicates a detected jitter value.

The QoS state table 400 includes at least one of the network delay timevalue, the packet loss value, and the QoS state value. The QoS statevalue in the QoS state table 400 is obtained from an intersection of thenetwork delay time value on an x-axis and the packet loss value on ay-axis. The QoS state value includes at least one of “Good,” “Fair,”“Poor,” and “Bad,” which indicate QoS classes.

FIG. 2 is a graph illustrating a QoS state table in the VoIP terminal ofFIG. 1. The graph is a network state mapping graph which is atwo-dimensional rendering of a three-dimensional graph having a networkdelay time plotted on an x-axis, a packet loss plotted on a y-axis, anda QoS state plotted on a z-axis.

The QoS state table 400 uses Equation 2 to calculate the network delaytime value in a busy state:Ti=(D_(g)S2)−D₁,  Equation 2where D_(g) is a one-directional delay value of G.114, and D1 is an RTPpacket processing delay value of a terminal.

The RTP packet processing delay value (D₁) of the terminal includes atleast one of a minimum processing time dependent on the type of CODECused in a busy state, a frame size of voice data, a capacity of a jitterbuffer, a type of an echo canceller, a delay time in a routine forenhancing quality of voice, and an additional network functionprocessing time (NAT, IPsec, etc.) used in a terminal.

The VoIP terminal includes a logging function for performing selectivestorage only when a quality issue is caused in network stateinformation.

FIG. 4 illustrates a circular queue used to limit data storage capacityin the VoIP terminal of FIG. 1. As shown in FIG. 4, the VoIP terminallimits maximum storage capacity of stored network state data using thecircular queue.

Detailed descriptions of typical functions and operations of theabove-mentioned components will be omitted.

A VoIP terminal is generally connected to an IP network (Internet) andperforms real time communication through RTP and RTCP.

A VoIP terminal monitoring the QoS of the network is referred to as a“transmitting VoIP terminal,” and a VoIP terminal performing real-timecommunication with the transmitting VoIP terminal is referred to as a“receiving VoIP terminal.”

The transmitting VoIP terminal 1 of FIG. 1 receives an RTP packet and anRTCP packet from a receiving VoIP terminal 2-1, 2-2, or 2-n.

In the transmitting VoIP terminal 1, the first detector 100 detects apacket loss value and a jitter value.

The second detector 200 measures an RTT value with respect to thereceiving VoIP terminal 2-1, 2-2, or 2-n. That is, the transmitting VoIPterminal 1 transmits an RTCP packet to the receiving VoIP terminal 2-1,2-2, or 2-n, and upon receipt of the RTCP packet, the receiving VoIPterminal 2-1, 2-2, or 2-n returns the RTCP packet to the transmittingterminal. In this case, the receiving VoIP terminal 2-1, 2-2, or 2-nincludes information about delay time, measured from receipt of the RTCPpacket to transmission of the RTCP packet, in the RTCP packet, andtransmits the RTCP packet with the delay time information to thetransmitting VoIP terminal 1. The transmitting VoIP terminal 1calculates the RTT value from the received information and timeinformation of the RTCP packet transmitted/received by the transmittingVoIP terminal 1.

In the transmitting VoIP terminal 1, the second detector 200 then addsthe calculated RTT value to the jitter value detected by the firstdetector 100 to obtain a time-axis index value.

The controller 300 ofthe transmitting VoIP terminal 1 then obtains a QoSstate value from the packet loss value and the time-axis index value,which are obtained by the first detector 100 and the second detector200, respectively, and compares the obtained QoS state value to the QoSstate table 400 to display the QoS state. The controller 300 employsEquation 1 to calculate a time-axis index value.

The QoS state table 400 includes at least one of the network delay timevalue, the packet loss value, and the QoS state value. The QoS statevalue in the QoS state table 400 is obtained from an intersection of thenetwork delay time value on an x-axis and the packet loss value on ay-axis.

FIG. 3 illustrates a QoS state of a network in the VoIP terminal ofFIG. 1. As shown in FIG. 3, the QoS state value includes at least one of“Good,” “Fair,” “Poor,” and “Bad,” which indicate QoS classes.

The QoS state table 400 employs Equation 2 to calculate the networkdelay time value in a busy state.

The VoIP terminal includes a logging function for performing selectivestorage only when a quality issue is caused in network stateinformation. As shown in FIG. 4, the VoIP terminal limits maximumstorage capacity of stored network state data using a circular queue.

A QoS monitoring method in a VoIP terminal having the above-describedconfiguration will be described with reference to FIG. 5, which is aflowchart illustrating a QoS monitoring method in a VoIP terminalaccording to an exemplary embodiment of the present invention.

First, a packet loss value and a jitter value for an RTP session aredetected from RTCP and RTP packets which are received from a terminal ina busy state, and an RTT value is calculated (S1).

The detected jitter and RTT values are then added to each other toobtain a time-axis index value (S2).

A QoS state value is then obtained from the packet loss value andtime-axis index value, and the obtained QoS state value is compared tothe QoS state table 400 to display the QoS state (S3). In step S3, inwhich the QoS state value is compared to the QoS state table 400 todisplay the QoS state, Equation 1 is used to calculate the time-axisindex value.

In step S3, in which the QoS state value is compared to the QoS statetable so as to display the QoS state, the QoS state table 400 employsEquation 2 to calculate the network delay time value in a busy state.

The QoS state table 400 includes at least one of the network delay timevalue in a busy state, the packet loss value, and the QoS state value.The QoS state value is obtained from an intersection of the networkdelay time value on the x-axis and the packet loss value on the y-axis,and includes at least one of “Good,” “Fair,” “Poor,” and “Bad,” whichindicate QoS classes.

The network QoS monitoring method includes a logging function forperforming selective storage only when a quality issue is caused innetwork state information. Maximum storage capacity of stored networkstate data is limited by a circular queue.

According to another exemplary embodiment of present invention, a QoSmonitoring device includes the first detector 100, the second detector200, the controller 300, and the QoS state table 400 of FIG. 1.

The first detector 100 detects a packet loss value and a jitter valuefrom the RTCP packet received from the terminal in communication overthe IP network 3.

The second detector 200 calculates an RTT value from an RTCP packetcarrying control information of an RTP packet which is received from aterminal in communication over the IP network 3, and adds the jittervalue detected by the first detector 100 to the RTT value to obtain atime-axis index value.

The controller 300 obtains a QoS state value from the packet loss valueand the time-axis index value, which are obtained by the first detector100 and the second detector 200, respectively, and compares the obtainedQoS state value to the QoS state table 400 to display a QoS state of thenetwork. The controller 300 uses Equation 1 to calculate the time-axisindex value.T_(m)=D_(r)+(W_(j)SJ),  Equation 1where T_(m) indicates a delay time value measured by the terminal, D_(r)indicates an RTT value calculated by the terminal, W_(j) indicates aweight of a jitter value, and J indicates a detected jitter value.

The QoS state table 400 includes at least one of the network delay timevalue, the packet loss value, and the QoS state value. The QoS statevalue in the QoS state table 400 is obtained from an intersection of thenetwork delay time value on an x-axis and the packet loss value on ay-axis. The QoS state value includes at least one of “Good,” “Fair,”“Poor,” and “Bad,” which indicate QOS classes.

As mentioned above, FIG. 2 is a network state mapping graph illustratinga QoS state table. The network state mapping graph is a two-dimensionalrendering of a three-dimensional graph having a network delay timeplotted on an x-axis, a packet loss plotted on a y-axis, and a QoS stateplotted on a z-axis.

The QoS state table 400 uses Equation 2 to calculate the network delaytime value in a busy state:Ti=(D_(g)S2)−D₁,  Equation 2where D_(g) is a one-directional delay value of G.114, and D₁ is an RTPpacket processing delay value of a terminal.

The RTP packet processing delay value (D₁) of the terminal includes atleast one of a minimum processing time dependent on the type of CODECused in a busy state, a frame size of voice data, a capacity of a jitterbuffer, a type of an echo canceller, a delay time in a routine forenhancing quality of voice, and an additional network functionprocessing time (NAT, IPsec, etc.) used in a terminal.

With the VoIP terminal having the QoS monitoring function and the QoSmonitoring method according to the embodiments of the present invention,it is possible for a user of the VoIP terminal to monitor the QoS stateof the network in real time in a busy state.

It is also possible to provide more exact monitoring data by determiningthe range of QoS in view of the type and features of the VoIP terminal.The monitoring result is displayed as one value, not sub-divided intoseveral items, so that a user easily understands the monitoring result.

Sub-divided QoS data can be provided by a logging function, so thatskilled persons can conduct detailed analysis. It is also possible tosave a memory of a VoIP terminal by logging data only when a problemoccurs, and to compress and provide only data having high availability.

While the present invention has been described with reference toexemplary embodiments thereof, it will be understood by those skilled inthe art that various changes in form and detail may be made thereinwithout departing from the scope of the present invention as defined bythe following claims.

1. A VoIP terminal for detecting a QoS state value from RTP and RTCPpackets received from a terminal in communication over a network, andfor comparing the detected QoS state value to a preset QoS state table.2. The VoIP terminal according to claim 1, wherein the VoIP terminalcomprises: a first detector for detecting a packet loss value and ajitter value from the RTCP packet received from the terminal incommunication over the network; a second detector for calculating an RTTvalue from the RTP and RTCP packets received from the terminal incommunication over the network, and for adding the jitter value detectedby the first detector to the RTT value to obtain a time-axis indexvalue; and a controller for detecting the QoS state value from thepacket loss value and the time-axis index value which are obtained bythe first detector and the second detector, respectively, and forcomparing the detected QoS state value to the QoS state table so as todisplay the QoS state.
 3. The VoIP terminal according claim 2, whereinthe controller calculates the time-axis index value using the followingequation:T_(m)=D_(r)+(W_(j)SJ), where T_(m) indicates a delay time value measuredby the terminal, D_(r) indicates an RTT value calculated by theterminal, W_(j) indicates a weight of a jitter value, and J indicates adetected jitter value.
 4. The VoIP terminal according to claim 1,wherein the QoS state table includes at least one of a network delaytime value, the packet loss value, and the QoS state value.
 5. The VoIPterminal according to claim 4, wherein the QoS state value of the QoSstate table is obtained from an intersection between the network delaytime value on an x-axis and the packet loss value on a y-axis.
 6. TheVoIP terminal according to claim 1, wherein the QoS state table is usedto calculate a network delay time value in a busy state using thefollowing equation:Ti=(D_(g)S2)−D₁, where D_(g) is a one-directional delay value of G. 114,and D₁ is an RTP packet processing delay value of a terminal.
 7. TheVoIP terminal according to claim 6, wherein the RTP packet processingdelay value (D1) of the terminal includes at least one of a minimumprocessing time dependent on a type of CODEC used in a busy state, aframe size of voice data, a capacity of a jitter buffer, a type of anecho canceller, a delay time in a routine for enhancing quality ofvoice, and an additional network function processing time (NAT, IPsec,etc.) used in the terminal.
 8. The VoIP terminal according claim 1,wherein the VoIP terminal includes a logging function for performingselective storage only when a quality issue is caused in network stateinformation.
 9. A QoS monitoring method in a VoIP terminal, the methodcomprising the steps of: detecting a packet loss value and a jittervalue for an RTP session from an RTCP packet received from a terminal incommunication; calculating an RTT value; adding the detected jittervalue to the RTT value to obtain a time-axis index value; obtaining aQoS state value from the detected packet loss value and the time-axisindex value; and comparing the obtained QoS state value to a QoS statetable to display a QoS state.
 10. The method according to claim 9,wherein a network delay time value in a busy state is calculated usingthe QoS state table and using the following equation:Ti=(D_(g)S2)−D₁, where D_(g) is a one-directional delay value of G.114,and D1 is an RTP packet processing delay value of a terminal.
 11. Themethod according to claim 9, wherein the QoS state table comprises atleast one of a network delay time value in a busy state, the packet lossvalue, and the QoS state value.
 12. The method according to claim 11,wherein the QoS state value in the QoS state table is obtained from anintersection of the network delay time value on an x-axis and the packetloss value on a y-axis.
 13. The method according to claim 11, whereinthe RTP packet processing delay value of the terminal includes at leastone of a minimum processing time dependent on a type of CODEC used in abusy state, a frame size of voice data, a capacity of a jitter buffer, atype of an echo canceller, a delay time in a routine for enhancingquality of voice, and an additional network function processing time(NAT, IPsec, etc.) used in the terminal.
 14. The method according claim9, wherein the step of comparing the obtained QoS state value to a QoSstate table to display a QoS state comprises calculating the time-axisindex value using the following equation:T_(m)=D_(r)+(W_(j)SJ), where T_(m) indicates a delay time value measuredby the terminal, D_(r) indicates an RTT value calculated by theterminal, W_(j) indicates a weight of a jitter value, and J indicates adetected jitter value.
 15. A QoS monitoring device, comprising: a QoSstate table including a network delay time value, a packet loss value,and a QoS state value; a first detector for detecting a packet lossvalue and a jitter value from an RTCP packet received from a terminal incommunication; a second detector for calculating an RTT value from anRTP packet and the RTCP packet which are received from the terminal incommunication, and for adding the jitter value detected by the firstdetector to the RTT value to obtain a time-axis index value; and acontroller for obtaining a QoS state value from the packet loss valueand the time-axis index value, which are obtained by the first detectorand the second detector, respectively, and for comparing the obtainedQoS state value to the QoS state table to display a QoS state of thenetwork.
 16. The device according to claim 15, wherein a network delaytime value in a busy state is calculated using the following equation:Ti=(D_(g)S2)−D₁, where D_(g) is a one-directional delay value of G.114,and D₁ is an RTP packet processing delay value of a terminal.
 17. Thedevice according to claim 16, wherein the RTP packet processing delayvalue (D₁) of the terminal includes at least one of a minimum processingtime dependent on a type of CODEC used in a busy state, a frame size ofvoice data, a capacity of a jitter buffer, a type of an echo canceller,a delay time in a routine for enhancing quality of voice, and anadditional network function processing time (NAT, IPsec, etc.) used inthe terminal.
 18. The device according claim 15, wherein the controllercalculates the time-axis index value using the following equation:T_(m)=D_(r)+(W_(j)SJ), where T_(m) indicates a delay time value measuredby the terminal, D_(r) indicates an RTT value calculated by theterminal, W_(j) indicates a weight of a jitter value, and J indicates adetected jitter value.